Apparatus for drilling wells



L. E. ZERBE ET AL 1,785,238

APPARATUS FOR DRILLING WELLS I Dec. 16, 1930.

Filed April 30, 1925 5 Sheets-Sheet l 94 a 94/ 6] i 66 5B 59 '7 55 00 no54 6 C 19 56 90 Ii Z 7 9? 71 4 6 1 55 67 1 4 v 41 5 M JWOWYHIOM Dec. 16,1930. E. ZERBE ET AL APPARATUS FOR DRILLING WELLS Filed April 30, 1925 5Sheets-Sheet 2 l l u l wn Uh gnuentom Dec. 16, 1930. E. ZERBE ET ALAPPARATUS FOR DRILLING WELLS Filed April 50, 1925 5 Sheets-Sheet 3 (1H0:new

Dec. 16, 1930. ZEIIQBIEL ET AL 1,785,238

APPARATUS FOR DRILLING WELLS Filed April 50, 1 25 5 Sheets-Sheet 4 F. 55 E 1 .fi -9 5 4' gmnntm Dec. 16, 1930. L, E ZERBE ET AL 1,785,238

APPARATUS FOR DRILLING WELLS Filed April 50, 1925 5 Sheets-Sheet 5amnion.

inc; drum as to continual Patented Dec. 16, I930 UNITED. STATES LEWIS E.ZERIBE, or MoNErA, CALIFORNIA,

PATENT OFFICE AND MERTON T. ARCHER, OI PITTSBURGH,

PENNSYLVANIA, ASSIGNOB S TO UNION TOOL COMPANY, OF TORRANCE, CALI-FORNIA, A CORPORATION OF CALIFORNIA I APPARATUS FOR- DRILLING WI ELLSApplication filed April 30, 1925. Serial No. 26,880.

This invention relates to well and other earth drilling apparatus andrefers particularly to the type of apparatus employed in the rotarymethod of drilling deep wells such as oil wells.

In the rotary method of drilling wells as generally carried out, thehole is made by the cutting action of a bit attached to and rotated by avertical pipe extending to the surface of the ground. Such a pipe isknown in the art as a drill stem. The drill stem is swivelly sustainedat its upper end by a hoist consisting of a block and tackle connectedto a hoisting drum, which drum, with its associated driving andregulating appliances, is known in the art as the draw-.

works. By means of the drawworks, the percentage of the weight of thedrill stem which is permitted to rest upon the drill bit may becontrolled. During drillin operations the drilling bit is rotated by t erota-, tion of the entire drill stem which in turn is driven by aso-called rotary table disposed at the surface of the ground.

With such general type of rotar drilling apparatus, when manuallyoperate the control of the power applied to the rotary table forrotating the drill stem is independent of the means utilized forcontrolling the drawworks to regulate the percentage of the weight ofthe drill stem permitted to rest upon the drill bit. With such. anapparatus, in the normal drilling of a well the rotating torque upon thedrill stem is furnished by a source of power of some character which isnormally allowed to function uncontrolled by the operator and governedonly by the resistance encountered to the rotation of the drill stem andbit.- The: operator endeavors to maintain upon the drill stem thecorrect drilling torque by so manipulating-the hoistthe deepening of thehole and to constantly impose that correct feed pressure upon the bitwhich will maintain an efficient, safe drilling rate. It is impossible,however, for

the operator, due to the variations encountered in drilling, to maintainin this way such control over the drilling apparatus as will establish auniform drilling rate or uniy compensate for form torque loads or otherstrains upon the drillin apparatus. Whenever fluctuation is made mm thecorrect drillin conditions, the wear and damage upon the bit is greatlyincreased, danger of damaging the drilling apparatus is also increased,and the quantity and quality of hole made is decreased.

Certain automatic drilling apparatus have been designed for the drillingof deep oil wells intended to provide mechanism adapted to displace themanual control of. the feedmg pressure applied to'the bit and tosubstitute in lieu thereof automatic control of all the forces appliedto the drill stem so as to maintain correct and optimum drillingconditions. One of the principal difliculties with such automaticdrilling machines as have been heretofore devised is that they areunsuited for use in connection with the presthe same prime mover andmust be free to operate withoutinterference from. the automatic devicescontrolling actual drilling. These lprior devised automatic drillingmachines ave been unsuited and unsatisfactory for practical use for thereason that. they cannot be employed without impracticable displacementor extensive readaptation of the necessary auxiliary drilling apparatus.

It is the primary object of the present invention to provide anautomatic drilling apparatus for the drilling of wells which is adaptedfor practical or commercial use, and which can be simply and easilyinstalled without expensive changes in the apparatus at resent in use'inthe usual well drilling rig. y this invention we not only provide suchan automatic drillingapparatus as is utilizthe efiicient performance andefiicient control of the necessar auxiliary apparatus of a well ri butwe a so provide an automatic driving evice which can be installed in thej able for well drilling while still permitting,

present ty e of well drilling rig with but slight mo ifications andadditions thereto. We thus are able to convert the well drilling rig nowin use to an automatic well drilling apparatus.

In carrying out the objects of the present invention, we preferablyutilize a differential gearing for connecting the prime mover of thewell drilling apparatus to the rotary table and to the drawworks so thatthe operations of the drawworks and rotary table are automaticallycontrolled. The differential employed is so constructed that it iscompact in size and readily inserted between the prime mover andhoisting drum of the present type drilling rig. We also employ in thisinvention such a type or form of differential gearing between the sourceof power and rotary table and hoisting mechanism as can be connectedthereto by the usual form of flexible chain drives.

In order that the differential provided may be adapted to be assembledin a compact form and, when so assembled, control the hoisting drum androtary table without extensive modifications therein and preferablythrough the usual form of chain drives, we provide a dilferent-ial inwhich one of the drivlng shafts is adapted to act also as a mainmounting or supporting shaft for the entire diiferential and the otherdriving shaft we construct of quill form revolvable on the saidsupporting shaft and thus provide both a compact and self-contained formof dilferential and also one adapted to withstand the heavy stresses ofthe drilling operations.

The invention and various further features, objects, and advantagesthereof will best be understood from a description of a preferred formor example of well drilling apparatus embodying the present invention,for which purpose reference is made to the accompanying drawings,illustrating one ex-.

ample of a well drilling apparatus embodyin the invention.

n the drawings:

Fig. 1 is an elevation of a well drilling apparatus embodying ourinvention, the usual apparatus employed in the o erations auxiliary todrilling not being illustrated, as theymay be of standard construction,and it will be recognized by those skilled in the art that thedrillingapparatus herein illustrated does not interfere or hinder the employmentof such standard auxiliary apparatus.

Fig. 2 is an enlarged plan View of the apparatus illustrated in Fig. 1,with the derrick removed.

Fig. 3 is a rear elevation of the apparatus, looking at the rear of thedifferential from the prime mover.

Fig. 4 is a side elevation of the apparatu shown in Fig. 3.

Fig. 5 is an enlarged end view of the differential and its mounting.

Figs. 6 and 7 together represent a complete longitudinal section 'of thedifferential.

Fig. 8 is atransverse section on the line 88 of Fig. 6.

Fig. 9 is a transverse section on the line 99 of Fig. 6.

Referring to the drawings, the well drilling apparatus there illustratedcomprises the customary well derrick 2 upon a suitable foundation 3. Thederrick 2 supports at its top a crown block 4: for the reception ofvarious lines 6 of a tackle and falls. 5 indicates a traveling blocksupported upon the lines 6 and connected thereby over the crown block 4to a hoisting drum 7 forming a part of the usual drawworks. Thetraveling block 5 swivelly supports a drill stem 8 which carries at itslower end a drilling bit 9. Thus by control of the drum 7 of thedrawworks, the percentage of the weight of the drill stem permitted torest upon the drilling bit 9 may be controlled during drillingoperations. The drill stem 8 is adapted to be rotated in use by a rotarytable 10 of any preferred or customary construction. In accordance withthe principles of this invention the drilling machine derives its powerfrom a prime mover 11 which may be of any type such as a steam engine,internal combustion engine, or electrical motor. Preferably, this primemover 11 is placed rearwardly of the drum 7 of the drawworks from therotary table 10 in order that all of the drilling apparatus may bedisposed at one side of the well rig 2, leaving the remainder of the rigfree for the installment of auxiliary apparatus and for the performanceof other auxiliary operations.

The prime mover 11 is connected by suitable means such as a chain drive12 to a differential 13, from which the force or power from the primemover 11 is transferred to the rotary table 10 and hoisting drum 7 insuch manner as to automatically operate those parts. The differential 13is of special construction so that it is adapted to withstand the heavydrilling stresses and is in a compact and self-contained form and can beconveniently disposed between the hoisting drum 7 and the prime mover 11with its driving shafts parallel to the axis of the draw-works. It canbe made as a unit assembly carrying all its parts and elements upon asingle base so that it can be installed as a unit in the drilling rigwithout requiring assemblage when installed.

The construction of the differential is best illustrated in Figs. 6 and7, the differential being provided with a main shaft 14 supported at. ornear itsends by bearing blocks 15 and 16 respectively mounted uponI-beams 17 1 afiixed to the floor timbers of the derrick 2. This mainshaft 14 serves to support the eny asa collar by tire differential onsaid bearings and 16 and thus acts as a supporting shaft for otheroperating parts of the differential and in addition thereto is itselfone of the driving shafts of the differential. The shaft 14 carries abeveled gear 18 having a hub 19 acting which the beveled gear 18 isrigidly held to the shaft 14 by a ke 20.

21 indicates a second driving s aft of the differential, which drivingshaft'is of quill form and is mounted on the main shaft 14 by rollerbearings 22 and 23 at its respective ends. These bearings are heldspaced apart by a sleeve 24 therebetween. The inner end of bearing 22abuts the end of the hub 19 of the beveled gear 18 and the outer end ofthe bearing 23 engages an inturned flange 24 on the quill shaft. 21 andthe bearing is thus held from outward movement. The quill driving shaft21 is provided with an enlarged bore 26 between the roller bearings 22and 23 in order to form a lubricant reservoir, as will hereinafter bepointed out. As later pointed out in operation the shaft 21 rotatesrapidly relative to the supporting shaft 14 and the roller bearings 22and 23are preferred to withstand the stresses developed at-high speed.

The inner end of the quill driving shaft 21 is keyed to a beveled gear27 by which it is driven. The gears 18 and 27 mesh with a inion ear 28.One or more of such inion gears 28 may be provided meshing with thebeveled gears 18 and 27 the pinion gear or gears 28 being mounted upon aspider 29 v which is secured to a gear housing or case 30.

The pinion gears 28 are provided with bronze or roller radial and thrustbearings 28*- and 29'? respectively. The gear housing or case 30provides annular chambers 31 and 32 respectively at both sides of thegearing for the reception of lubricant, from which chamber it isconveyed through suitable holes and channels to all other parts of thedifferential and to the reservoir 26 provided by the quill shaft '21.One end of the housing or case 30 is pro-.

' vided with a hub 33 mounted by a bronze or roller bearing on the mainsupporting shaft 14. The hub 33 also serves to mount a sprocket wheel 34keyed thereon as indicated at 35,

and bolted to the sides of the gearing housing or-case 30. The sprocketwheel 34 is driven by the sprocket chain 12 from the prime mover '11. I

The other end of the gear housing or case 30 is provided with a hub 36mounted through bronze or roller bearings 37 upon the hub of the beveledgear 27 carried by the quill shaft 21; said hub 36 also engages a bronzeor roller thrust bearing 38 engaging the back face 'of the beveled gear27 from which the end thrust of the beveled gear 27 and quill shaft 21-rigid therewith is received.

. The end of the quill shaft 21 is provided with a clutch face adaptedto be engaged by the clutch face of a quill clutch 41 mounted on themain shaft 14'and keyed thereto. This clutch in operation may beutilized to lock the quill shaft 721 to the main shaft 14; thedifferential gearing is then frozen and the whole differential operatesas a single rigid shaft.

Rotatably mounted on the quill shaft 21 near its upper end is a sprocketWheel 42. This'sprocket wheel 42 at its inner end has a clutch faceengageabl'ewith the clutch face of a clutch 45; the clutch 45 abuts theend of the gear housing 30 and is slidably keyed upon the quill shaft 21as indicated at 46. At the opposite side of the gearing, the main shaft14 rotatably mounts two sprocket Wheels 47 and 48 respectively ofdifferent sizes and having clutch faces adapted to be selectivelyengaged by clutch faces of a double clutch 49 disposed therebetween andslidably keyed on the main shaft 14. v

The gear housing 30 may have its chambers '31 and 32 filled withlubricant through a plug 50. From the chambers 31 and 32 the entirebearings for the differential are lubricated, the lubricant passing fromthe chamber 31 through holes '51 to the bearing 37, through holes 51 tobearings 28" and 29*, and between the gears through channel 52 andradial ducts 53 in the quill shaft 21 to the chamber 26 formed by theenlarged bore of the quill shaft, from which it may pass to the highspeed roller bearings of such shaft. In this manner all of the lubricantcan be supplied from, one point to all the bearings of the differential.

Preferably, means are provided on each of the driving shafts 14 and 21to impose an artificial restraint to their rotation when desired. Thepreferred form of such means are the brake drums 54 and 55, for theshafts 14 and 21 respectively. The brake drum 54 is keyed on the shaft14 beyond the sprocket wheels .47 and 48 and the brake drum 55 isrigidly secured to the sprocket wheel 42 to be driven by the quill shaft21.

In order that such difierential may be employed in driving the rotarytable and hoisting drum without requiring material changes in thepresent drilling apparatus, or the addition of further apparatus forattaching the differential thereto, use is made of the cus-" tomary lineshaft 56 of the draw-works in connecting the differential to the rotarytable 10 and the hoisting drum. For this purpose, said line shaft ismade to revolvably mount a collar 57 carrying two sprocket wheels 58 and59. A chain '60 drives the sprocket wheel 58 from the sprocket wheel 42driven by the quill shaft 21 of the differential and the sprocket wheel59 carries a chain 61 driving the rotary table 10. In performing thisfunction, the customary line shaft is utilized merely as an axle for thesprockets 58 and 59 of the rotary table drive. The line shaft 56 alsoserves as a countershaft between the differential 13 and hoisting drum 7permitting a plurality of changes in the ratios of the relative speedsof the main shaft 14 and the drum 7. For this purpose, the sprocketwheels 47 and 48 which are adapted to be selectively driven by the mainshaft 14 drive sprockets 64 and on the line shaft 56 by means of chains62 and 63, said sprocket wheels 64 and 65, being indicated as rigid withthe line shaft 56. The connections between the line shaft '56 andhoisting drum 7 are the usual selective chain drives therebetween. Inthe ordinary drawworks there are provided two or more selective chaindrives between the line shaft and drum, of which 66 and 67 respectivelyindicate different drives and their respective chains, sprockets andclutches. The line shaft 56 is indicated as disposed, as usual, with itsaxis parallel to the axis of the drum 7 of the drawworks and disposedthereabove.

The differential 13 thus described is of compact form and so constructedas to have both its driving connections directly through the medium ofthe customary line shaft, and is thus adapted to be disposed close tothe drawworks, and with its axis parallel with the axes of the lineshaft and drum. Thereby a compact automaticwell drilling controllingmechanism is provided which can be installed or embodied in the usualtype of well drilling apparatus now in use simply by bodily insertingthe self-contained differential and associated parts between theordinary prime mover and drawworks and the placing of a few additional srocket wheels and chain drives on the line s aft.-'

The different clutches of the apparatus are preferably connected so thatthey maybe operated at the common operating point of the drillingapparatus located at the right hand end as usual of the drawworks whenfacing the rotary table. For this purpose,

one of the inner posts of the derrick mounts a lever control lockingplate having ways and grooves therein for locking levers 81, 82 and 83in their different proper operating positions, the levers 81, 82 and 83being employed to control the clutches of the differential. The lever 81is connected by a rocker arm 84 and reach rod 85 to a yoke 86controlling the double clutch 49 which selectively engages sprocketwheels 47 and 48. The lever 82 operates through rocker arms 87, reachrod 88 and yoke 89 to control the quill clutch 41 utilized inlocking thequill shaft 21 to the main shaft 14 when it is desired to operate thedifferential as one rigid shaft. The lever 83 is connected by rocker arm90, reach rod 91, and yoke 92 to clutch 45 which engages the sprocketwheel 42 which drives the rotary table 10.

The clutches on the hoisting drum 7 of the drawworks are operated asusual by foot levers 93 and 94 of standard construction disposed underthe lever control locking plate so that the entire control apparatus iscentered at the customary place from which all drilling operations areconventionally controlled. The drums 54 and 55 also have operatinghandles 95 extending to the common control position where they may bemanually operated at will to apply progressive resistance to therotation of the shafts on which the respective drums are mounted.

Means 96 are also provided for each drum by which the drums may be setto offer a fixed resistance or restraint on the shaft connectedtherewith. Such means 96 are indicated as rods 97 fixed at one end andprovided with an adjusting nut for tightening the brake bands of thedrums in any desired position.

We will now describe the method and procedure followed in utilizing ourimproved apparatus:

In describing first the normal automatic operation of the drillingapparatus, the prime mover 11 continuously supplies power to thedifferential 13 through chain drive 12 tending to rotate the spidermounting the pinion gear 28. This action imposes upon the main shaft 14and the quill shaft 21 a definite ratio of force depending upon therelative size of the gears 18 and 27. With these gears of equal size asindicated, the force tending to rotate the main shaft 14 will be equalto the force tending to rotate the quill shaft 21. The force tending torotate the quill shaft 21 is made to pass through the chain drive 60 andthe chain drive 61 to the rotary table 10, by bringing the clutch 45,through manipulation of lever 83, into position so that the sprocketwheel 42 is driven by the quill shaft 21.

The force applied to the main shaft 14 is utilized to exert a liftingforce upon the drill stem in order to govern the feed pressure which isapplied to the bit. In operation, the weight of the drill stem exerts aforce through line 6 upon the drawworks tending to unreel the line andpermit the drill stem 8 to lower. By selective utilization of the chaindrive connections between the main shaft and the drawworks, this forcecan be opposed by various forces originating from the prime mover 11. Itwill be readily understood that whenever the force applied tothedrawworks tending to lift the drill stem is in balance with the contraryforce supplied by the weight of the drill stem, the hoisting apparatuswill be.

in equilibrium and the main shaft 14 held stationary. lVith any definiteset speed ratio between the main shaft 14 and hoisting drum 7, theapparatus will automatically bring itself to a state of equilibrium whenthe force due to the suspended weight of the drill stem is equal to theforce applied by the-prime mover tending to lift the drill stem. Themagnitude of the lifting force is thus determined by the selection ofthe speed ratio between the main shaft 14 and the hoisting drum 7 andthe main shaft 14 for the reason that in drilling operations differenttypes of bits are employed or different characters of formation drilledupon may require a differ- I ent feeding pressure upon the bits, andmoreover, as the hole is progressively lengthened due to the increase inweight of the lengthened drill stem, it is necessary to but applyincreased lifting forces upon the drill stem if the same feedingpressure or torque is to be maintained.

The employment of the line shaft 56 and the use of such line shaft as acountershaft for providing a plurality of selectively utilizable chaindrives between the main shaft 14 and the drum 7 not only allows theirspeed ratio to be Ivaried, but accomplishes this purpose withoutexpensive modifications in the present form of drilling apparatus. Italso accomplishes such variation in speed ratio with apparatus compactin form and of the character of drive connection which has been foundbest suited for the work, due to the 'inherent slack in the cliains towithstand the shocks of drilling operations.

It will be readily apparent that the drilling apparatus once set inoperation maintains upon the drill stem a definite torque with continualincrease or decrease of the feeding pressure appliedto the bit as thedifferent conditions of drilling require, the feed of the drill stembeing entirely automatic.

It will also be apparent that the purpose and mode of operation of thechain drive between the main shaft 14, line shaft 56, and the chaindrives betwen the line shaft 56 and hoisting drum 7 do not require theclutches for selectively setting in action the different chain-drives tobe located in any particular place. Thus the clutches for the chaindrive between the line shaft 56 and drum 7 might be placed upon the lineshaft 56 instead of on the drum 7, and the clutches for the chain drivesbetween the main shaft 14 andthe line shaft 56 might be placed upon theline shaft.

instead of upon the main shaft 14. The invention includes, of course,all such'obvious vide a supplemental means for this control.

The brake drum 54 on the main shaft 14 may be utilized to apply aprogressively increasing resistance to the rotation of the main shaftcorresponding to a greater weight applied by the drill stem. The use ofthis drum 1s of special value in the early stages of the drilling, when,due to the fact that the drill stem is'of insuflicientweight, it isnotable to balance the rotating force required to impose a desiredtorque on the drill stem. :The drum 54 may be operated by either thehandles 95 or'the set control means 96.v Preferably for this operationthe set control means should be utilized to free the apparatus from anydependence upon'the skill of the operator.

The drum 54 on the main shaft 14 can also be utilized when the selectivechain drives will not place the desired torque upon the drill stem, dueto the reason that in one selective arrangement a lower torque than isde- 1 slred or any other operation in WhlCll'lt is desired to lift thedrill stem or to remove feed pressure therefrom without permitting therotary table to speed up or when it is desired to lift the drill stemand stop the rotation of the rotary table without disengaging the chaindrives. This brake 55 acts by imposing an additional resistance to therotation of the quill shaft which increases the force applied throughthe main shaft 14 to lift the drill stem. Also by this arrangement ofapparatus we are enabled to perfo'rman operation novel in the drillingof wells, thatis, stop the rotation of the drill stem by a man'- uallycontrolled device and without shutting down the prime mover 11 orwithout disengaging the prime mover 11 from a driving engagement withthe rotary table:

The quill clutch 41 keyed to the main shaft 14 engageablewith the quillshaft 21 to lock these shafts rigidly together provides a means forproper manipulation of the hoisting drum 7 when it is desired to hoistthe drill stem from the hole. When it is desired to lift the drillstemrwi'thout rotating it the quill clutch is brought intoengagementwith the quill shaft, as shown, and the clutch '45 connecting thesprocket wheel 42 with the .quill shaft 21 is disengaged by means of thelever 83. In this ase the entire power and force of the prime mover isapplied to lift the drill stem It isobvious. that in performing thisservice of lifting the drill stem, that'if instead of locking the quillshaft and main shaft together by the clutch 4,1, the main drivingsprocket 42 be left in engagement with the quill shaft but held .irmlyagainst rotation by the brake 55, an additional speed ratio may beobtained between the prime mover 11 and the drum 7 double that by anyother means.

It is also obvious that when by the use of the quill clutch 41 thedifferential mechanism is converted into asolid drive, it permits therotary machine to be rotated in either direction without the functioningof the differential.

'While the embodiment of the invention herein described is well adaptedto accomplish the purposes and objects of this invention, it isunderstood that various modifications may be made without departing fromthe spirit of the invention. This invention therefore is not limited tothe specific em bodiment described for the purpose of illustrating theprinciples of the invention, but includes all such modifications,changes, substitutions, and equivalents as come within the scope of theappended claims.

We claim 1. An apparatus for drilling wells, comprising a prime mover, adrill bit, means for rotating the drill bit, means for controlling thefeed pressure on the drill bit, a differential connecting the primemover with the rotating means and feed pressure control means, theconnection between the differential and feed pressure control meansconsisting of a plurality of chain drives selectively' utilizable forestablishing various speed ratios between the differential and feedpressure control means, said chain drive operating through the medium ofa counter-' shaft 2. In an automatic well drilling apparatus, thecombination of a hoisting drum, a rotary table, a prime mover, and adifferential driven by said prime mover and having its driving shaftsconnected by means of chain drives to the hoisting drum and rotary tablerespectively, the connection between the differential and hoisting drumincluding a plurality of selectively utilizable chain drives operativeto vary the speed ratio therebetween, the chain drives operating throughthe medium of a countershaft, the countershaft also serving as an axlefor sprockets forming art of the chain drive connection between t edifferential and rotary table.

' 3. In an automatic well drilling apparatus, the combination with arotary table, a hoisting drum, and a prime mover, of a differentialdriven by the prime mover and having one of its driving shafts extendingthrough the differential and provided with bearings at opposed sides ofthe differential gearing so as to function as a main supporting shaft,the other driving shaft being of quill form and revolvable thereon,

one of said driving shafts being operatably connected to the rotarytable, the other driving shaft being operatably connected to thehoisting drum.

4. In an automatic well drilling apparatus, the combination of a primemover, drill stem rotating means, drill stem hoisting means, and adifferential connecting the prime mover to the rotating and hoistingmeans, the differential having one of its driving shafts formed as amain supporting shaft for the differential, and the other driving shaftformed as a quill shaft revolvable on the main shaft, said differentialalso having a pinion gear carrying member rigid with the housing or caserotatable about the axis of the main shaft, the housing be ing carriedat one side by the supporting shaft, and at the other side by the quillshaft.

5. In an automatic well drilling apparatus, the combination of a primemover, drill stem rotating means, drill stem hoisting means, and adifferential operatably connecting the prime mover with the rotating andhoisting means, the differential having one of its driving shafts formedas a main supporting shaft, the other driving shaft being of quillconstruction mounted on the supporting shaft, the pinion gears of thedifferential being-carried by a housing and revolvable about the axis ofthe supporting shaft, the housing providing a lubricant chamber entirelyenclosing the differential gearing and in communication with thebearings between the quill shaft and main shaft and the bearings betweenthe housing, main shaft and quill shaft.

6. In an automatic well drilling apparatus, the combination of aprimemover, drill stem rotating means, drill stem hoist-ing means, and adifferential operably' connecting the prime mover with the rotating andhoisting means, the differential having one of its driving shafts formedas the main supporting shaft, the other driving shaft being of quillconstruction and'mounted on the supporting shaft, a connection betweensaid quill driving shaft and said drill stem rotating means, a pluralityof selectively utilizable chain drive connections between the mainsupport ing shaft and the drill stem hoisting means, including sprocketsmounted upon said main shaft, and clutch means for selectivelyconnecting said chain drive connections.

7. In an automatic well drilling apparatus, the combination of a primemover, drill stem rotating means, drill stem hoisting means,

and a differential operably connecting the prime mover with the rotatingand hoisting means, the differential having one of its driven shaftsformed as a main supporting shaft, the other driven shaft being of quillconstruction and mounted on the supporting shaft, the pinion gear of thedifferential being carried by a housing and revolvable about the axis ofthe supporting shaft, and a plurality of selectively utilizable chaindrive connections between the main supporting shaft and the drill stemhoisting means, said chain drive connections utilizing said main shaftas a mounting for sprockets thereof, and clutch means for selectivelyconnecting said chain drive connections.

8. In an automatic Well drilling apparatus, the combination of a primemover, drill stem rotating means, drill stem hoisting means, and adifferential operably connecting the prime mover and the rotating andhoisting means, the differential having one of its shafts formed as asupporting shaft for the differential, the other shaft being a quillshaft revolvable thereon, the pinion gears of the difierential beingcarried by a housing and revolvable about the axis of the supportingshaft.

9. In an automatic Well drilling apparatus, the combination of a primemover, drill stem rotating means, drill stem hoisting means, and adifferential operably connecting the prime mover and the rotating andhoisting means, the differential having one of its shafts formed as asupporting shaft for the diflerential, the other shaft being a quillshaft revolvable thereon, the pinion gears of the differential beingcarried by a housing and re volvable about the axis of the supportingshaft and the prime mover being connected to rotate the housing carryingthe pinion gears.

Signed at Torrance, Calif, this 6th day of March, 1925, and at Toledo,Ohio, this 18th day -of April, 1925, respectively.

LEWIS E. ZERBE. MERTON T. ARCHER.

